Efficient HTN to STRIPS Encodings for Concurrent Planning

Nicolas Cavrel, Damien Pellier, Humbert Fiorino

Abstract: The Hierarchical Task Network (HTN) formalism is used to express a wide variety of planning problems and many techniques have been proposed to solve them. A particular technique is to encode hierarchical planning problems as classical STRIPS planning problems. One advantage of this technique is to benefit directly from the constant improvements made by STRIPS planners. However, there are still few effective and expressive encodings. In this paper, we present the first HTN to STRIPS encodings allowing to generate concurrent plans. We show experimentally that these encodings not only outperform previous approaches on hierarchical IPC benchmarks but also produce more expressive solution plans.